Polyphaser sells a WK-1 weatherproofing kit for their devices that are not weatherized such as the IS-50 series. It looks like a plain sheet of weatherproofing tape like any other, such as might be used to seal coax connections.
I'm hoping to install the protector on a heavy copper bulkhead I got for a steal at a hamfest. Installed in such a way, I don't see how the assembly could be wrapped. The kit comes with instructions, which ostensibly include some clever way around this problem. However, I refuse to pay $17 for a piece of tape. What's a good way to weatherize these surge protectors?